Theory of transition times: Catalysis at rotating disk electrodes

An exact solution to the problem of convective diffusion to a rotating disk electrode in the limit of high Schmidt numbers, with a prescribed initial profile and current step conditions at the surface is presented. Based on this solution a current density-transition time relationship is established which, in the limit, reduces to a previously proposed expression that accounts for experiemntally observed deviations from the Sand equation. Applications of this theory in connection with the determination of rate parameters for electroactive species undergoing a catalytic reaction at the electrode surface are discussed.